1. Field of the Invention
The present invention relates to a display system for displaying the acting state of an automatic transmission for a vehicle.
2. Related Art
The automatic transmission for a vehicle is given a fundamental function to set a gear stage automatically on the basis of a running condition such as a vehicle speed or a throttle opening. On the other hand, the selection of the shift range, in which the engine braking is effected at a predetermined medium or lower gear stage or in which the gear stage to be set is limited to a predetermined medium or lower one, is manually made by the driver. In the prior art, the selection of that shift range is made by operating a shift lever which is located on the floor or steering column and so on. For this operation, the driver has to leave one hand from the steering wheel or has to turn the eyes temporarily from the front road. This raises operational problems to be improved.
In the invention disclosed in Japanese Patent Laid-Open No. 196118/1993 (JPA-5-196118), therefore, the steering handle is equipped with a switch, which is suitably turned ON/OFF to switch the shift range.
When the shift range is to be electrically switched by a switching operation, as described in the above publication, it is a current practice to provide up and down switches while considering the operability. On the other hand, there are a plurality of shift ranges to be selected by the switching operation. Thus, the switch to be used for selecting the shift ranges is constructed to output its signal, each time it is operated, but to fail to determine a specific acting state. Specifically, some switch is given a structure disabling the driver to know the actually set shift range.
In the shift range at a medium or lower speed, on the other hand, the engine braking is effected at a predetermined gear stage. If a shift range being set at a higher speed is switched to a shift range at a medium or lower speed while the vehicle is running, the engine braking state is caused simultaneously with the downshift. If the vehicle is then running at a high speed, the engine RPM grows excessively high, and the switching of the shift range is inhibited depending upon the vehicle speed.
When the shift range is thus electrically switched, the switch therefor may fail to display the actually set shift range, and the shift range may not be switched even by the switching operation. As different from the switching of the shift range by the lever operation, therefore, there is a disadvantage that the shift range cannot be known from the switching mechanism such as the switch.